5.3.10 Radio link failure related actions

38.3313GPPNRProtocol specificationRadio Resource Control (RRC)Release 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5.3.10.1 Detection of physical layer problems in RRC_CONNECTED

The UE shall:

1> if any DAPS bearer is configured, upon receiving N310 consecutive "out-of-sync" indications for the source SpCell from lower layers and T304 is running:

2> start timer T310 for the source SpCell.

1> upon receiving N310 consecutive "out-of-sync" indications for the SpCell from lower layers while neither T300, T301, T304, T311, T316 nor T319 are running:

2> start timer T310 for the corresponding SpCell.

5.3.10.2 Recovery of physical layer problems

Upon receiving N311 consecutive "in-sync" indications for the SpCell from lower layers while T310 is running, the UE shall:

1> stop timer T310 for the corresponding SpCell.

1> stop timer T312 for the corresponding SpCell, if running.

NOTE 1: In this case, the UE maintains the RRC connection without explicit signalling, i.e. the UE maintains the entire radio resource configuration.

NOTE 2: Periods in time where neither "in-sync" nor "out-of-sync" is reported by L1 do not affect the evaluation of the number of consecutive "in-sync" or "out-of-sync" indications.

5.3.10.3 Detection of radio link failure

The UE shall:

1> if any DAPS bearer is configured and T304 is running:

2> upon T310 expiry in source SpCell; or

2> upon random access problem indication from source MCG MAC; or

2> upon indication from source MCG RLC that the maximum number of retransmissions has been reached; or

2> upon consistent uplink LBT failure indication from source MCG MAC:

3> consider radio link failure to be detected for the source MCG i.e. source RLF;

3> suspend the transmission and reception of all DRBs and multicast MRBs in the source MCG;

3> reset MAC for the source MCG;

3> release the source connection.

1> else:

2> during a DAPS handover: the following only applies for the target PCell;

2> upon T310 expiry in PCell; or

2> upon T312 expiry in PCell; or

2> upon random access problem indication from MCG MAC while neither T300, T301, T304, T311 nor T319 are running; or

2> upon indication from MCG RLC that the maximum number of retransmissions has been reached; or

2> if connected as an IAB-node, upon BH RLF indication received on BAP entity from the MCG; or

2> upon consistent uplink LBT failure indication from MCG MAC while T304 is not running:

3> if the indication is from MCG RLC and CA duplication is configured and activated for MCG, and for the corresponding logical channel allowedServingCells only includes SCell(s):

4> initiate the failure information procedure as specified in 5.7.5 to report RLC failure.

3> else:

4> consider radio link failure to be detected for the MCG, i.e. MCG RLF;

4> discard any segments of segmented RRC messages stored according to 5.7.6.3;

NOTE: Void.

4> if AS security has not been activated:

5> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause ‘other’;-

4> else if AS security has been activated but SRB2 and at least one DRB or multicast MRB or, for IAB, SRB2, have not been setup:

5> store the radio link failure information in the VarRLF-Report as described in clause 5.3.10.5;

5> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause ‘RRC connection failure’;

4> else:

5> store the radio link failure information in the VarRLF-Report as described in clause 5.3.10.5;

5> if T316 is configured; and

5> if SCG transmission is not suspended; and

5> if the SCG is not deactivated; and

5> if neither PSCell change nor PSCell addition is ongoing (i.e. timer T304 for the NR PSCell is not running in case of NR-DC or timer T307 of the E-UTRA PSCell is not running as specified in TS 36.331 [10], clause 5.3.10.10, in NE-DC):

6> initiate the MCG failure information procedure as specified in 5.7.3b to report MCG radio link failure.

5> else:

6> initiate the connection re-establishment procedure as specified in 5.3.7.

A L2/L3 U2N Relay UE shall:

1> upon detecting radio link failure:

2> it either indicates to upper layers (to trigger PC5 unicast link release) or sends Notification message to the connected L2/L3 U2N Remote UE(s) in accordance with 5.8.9.10.

The UE shall:

1> upon T310 expiry in PSCell; or

1> upon T312 expiry in PSCell; or

1> upon random access problem indication from SCG MAC; or

1> upon indication from SCG RLC that the maximum number of retransmissions has been reached; or

1> if connected as an IAB-node, upon BH RLF indication received on BAP entity from the SCG; or

1> upon consistent uplink LBT failure indication from SCG MAC:

2> if the indication is from SCG RLC and CA duplication is configured and activated for SCG, and for the corresponding logical channel allowedServingCells only includes SCell(s):

3> initiate the failure information procedure as specified in 5.7.5 to report RLC failure.

2> else:

3> consider radio link failure to be detected for the SCG, i.e. SCG RLF;

3> if MCG transmission is not suspended:

4> initiate the SCG failure information procedure as specified in 5.7.3 to report SCG radio link failure.

3> else:

4> if the UE is in NR-DC:

5> initiate the connection re-establishment procedure as specified in 5.3.7;

4> else (the UE is in (NG)EN-DC):

5> initiate the connection re-establishment procedure as specified in TS 36.331 [10], clause 5.3.7;

5.3.10.4 RLF cause determination

The UE shall set the rlf-Cause in the VarRLF-Report as follows:

1> if the UE declares radio link failure due to T310 expiry:

2> set the rlf-Cause as t310-Expiry;

1> else if the UE declares radio link failure due to the random access problem indication from MCG MAC:

2> if the random access procedure was initiated for beam failure recovery:

3> set the rlf-Cause as beamFailureRecoveryFailure;

2> else:

3> set the rlf-Cause as randomAccessProblem;

1> else if the UE declares radio link failure due to the reaching of maximum number of retransmissions from the MCG RLC:

2> set the rlf-Cause as rlc-MaxNumRetx;

1> else if the UE declares radio link failure due to consistent uplink LBT failures:

2> set the rlf-Cause as lbtFailure;

1> else if the IAB-MT declares radio link failure due to the reception of a BH RLF indication on BAP entity:

2> set the rlf-Cause as bh-rlfRecoveryFailure.

1> else if the UE declares radio link failure due to T312 expiry:

2> set the rlf-Cause as t312-Expiry;

5.3.10.5 RLF report content determination

The UE shall determine the content in the VarRLF-Report as follows:

1> clear the information included in VarRLF-Report, if any;

1> set the plmn-IdentityList to include the list of EPLMNs stored by the UE (i.e. includes the RPLMN);

1> set the measResultLastServCell to include the cell level RSRP, RSRQ and the available SINR, of the source PCell (in case HO failure) or PCell (in case RLF) based on the available SSB and CSI-RS measurements collected up to the moment the UE detected failure;

1> if the SS/PBCH block-based measurement quantities are available:

2> set the rsIndexResults in measResultLastServCell to include all the available measurement quantities of the source PCell (in case HO failure) or PCell (in case RLF), ordered such that the highest SS/PBCH block RSRP is listed first if SS/PBCH block RSRP measurement results are available, otherwise the highest SS/PBCH block RSRQ is listed first if SS/PBCH block RSRQ measurement results are available, otherwise the highest SS/PBCH block SINR is listed first, based on the available SS/PBCH block based measurements collected up to the moment the UE detected failure;

1> if the CSI-RS based measurement quantities are available:

2> set the rsIndexResults in measResultLastServCell to include all the available measurement quantities of the source PCell (in case HO failure) or PCell (in case RLF), ordered such that the highest CSI-RS RSRP is listed first if CSI-RS RSRP measurement results are available, otherwise the highest CSI-RS RSRQ is listed first if CSI-RS RSRQ measurement results are available, otherwise the highest CSI-RS SINR is listed first, based on the available CSI-RS based measurements collected up to the moment the UE detected failure;

1> set the ssbRLMConfigBitmap and/or csi-rsRLMConfigBitmap in measResultLastServCell to include the radio link monitoring configuration of the source PCell (in case HO failure) or PCell (in case RLF), if available;

1> for each of the configured measObjectNR in which measurements are available:

2> if the SS/PBCH block-based measurement quantities are available:

3> set the measResultListNR in measResultNeighCells to include all the available measurement quantities of the best measured cells, other than the source PCell (in case HO failure) or PCell (in case RLF), ordered such that the cell with highest SS/PBCH block RSRP is listed first if SS/PBCH block RSRP measurement results are available, otherwise the cell with highest SS/PBCH block RSRQ is listed first if SS/PBCH block RSRQ measurement results are available, otherwise the cell with highest SS/PBCH block SINR is listed first, based on the available SS/PBCH block based measurements collected up to the moment the UE detected failure;

4> for each neighbour cell included, include the optional fields that are available;

2> if the CSI-RS based measurement quantities are available:

3> set the measResultListNR in measResultNeighCells to include all the available measurement quantities of the best measured cells, other than the source PCell (in case HO failure) or PCell (in case RLF), ordered such that the cell with highest CSI-RS RSRP is listed first if CSI-RS RSRP measurement results are available, otherwise the cell with highest CSI-RS RSRQ is listed first if CSI-RS RSRQ measurement results are available, otherwise the cell with highest CSI-RS SINR is listed first, based on the available CSI-RS based measurements collected up to the moment the UE detected radio link failure;

4> for each neighbour cell included, include the optional fields that are available;

2> for each neighbour cell, if any, included in measResultListNR in measResultNeighCells:

3> if the UE supports RLF-Report for conditional handover and if the neighbour cell is one of the candidate cells for which the reconfigurationWithSync is included in the masterCellGroup in the MCG VarConditionalReconfig at the moment of the detected failure:

4> set choConfig in MeasResult2NR to the execution condition for each measId within condTriggerConfig associated to the neighbour cell within the MCG VarConditionalReconfig;

4> if the first entry of choConfig corresponds to a fulfilled execution condition at the moment of handover failure, or radio link failure; or

4> if the second entry of choConfig, if available, corresponds to a fulfilled execution condition at the moment of handover failure, or radio link failure:

5> set firstTriggeredEvent to the execution condition condFirstEvent corresponding to the first entry of choConfig or to the execution condition condSecondEvent corresponding to the second entry of choConfig, whichever execution condition was fulfilled first in time;

5> set timeBetweenEvents to the elapsed time between the point in time of fullfilling the condition in choConfig that was fulfilled first in time, and the point in time of fullfilling the condition in choConfig that was fulfilled second in time, if both the first execution condition corresponding to the first entry and the second execution condition corresponding to the second entry in the choConfig were fullfilled;

1> for each of the configured EUTRA frequencies in which measurements are available;

2> set the measResultListEUTRA in measResultNeighCells to include the best measured cells ordered such that the cell with highest RSRP is listed first if RSRP measurement results are available, otherwise the cell with highest RSRQ is listed first, and based on measurements collected up to the moment the UE detected failure;

3> for each neighbour cell included, include the optional fields that are available;

NOTE 1: The measured quantities are filtered by the L3 filter as configured in the mobility measurement configuration. The measurements are based on the time domain measurement resource restriction, if configured. Exclude-listed cells are not required to be reported.

1> set the c-RNTI to the C-RNTI used in the source PCell (in case HO failure) or PCell (in case RLF);

1> if the failure is detected due to reconfiguration with sync failure as described in 5.3.5.8.3, set the fields in VarRLF-report as follows:

2> set the connectionFailureType to hof;

2> if the UE supports RLF-Report for DAPS handover and if any DAPS bearer was configured while T304 was running:

3> set lastHO-Type to daps;

3> if radio link failure was detected in the source PCell, according to clause 5.3.10.3:

4> set timeConnSourceDAPS-Failure to the time between the initiation of the DAPS handover execution and the radio link failure detected in the source PCell while T304 was running;

4> set the rlf-Cause to the trigger for detecting the source radio link failure in accordance with clause 5.3.10.4;

2> if the UE supports RLF-Report for conditional handover and if configuration of the conditional handover is available in the MCG VarConditionalReconfig at the moment of the handover failure:

3> if the UE executed a conditional handover toward target PCell according to the condRRCReconfig of the target PCell:

4> set timeSinceCHO-Reconfig to the time elapsed between the execution of the last RRCReconfiguration message including reconfigurationWithSync for the target PCell of the failed conditional handover, and the reception in the source PCell of the last conditionalReconfiguration including the condRRCReconfig of the target PCell of the failed conditional handover;

3> else:

4> set timeSinceCHO-Reconfig to the time elapsed between the execution of the last RRCReconfiguration message including reconfigurationWithSync for the target PCell of the failed handover, and the reception in the source PCell of the last conditionalReconfiguration including the condRRCReconfig;

3> set choCandidateCellList to include the global cell identity, if available, and otherwise to the physical cell identity and carrier frequency of each of the candidate target cells for conditional handover included in condRRCReconfig within the MCG VarConditionalReconfig at the time of the failed handover, excluding the candidate target cells included in measResulNeighCells;

2> if the UE supports RLF-Report for conditional handover and if the last executed RRCReconfiguration message including reconfigurationWithSync was concerning a conditional handover:

3> set lastHO-Type to cho;

2> set the nrFailedPCellId in failedPCellId to the global cell identity and tracking area code, if available, and otherwise to the physical cell identity and carrier frequency of the target PCell of the failed handover;

2> include nrPreviousCell in previousPCellId and set it to the global cell identity and tracking area code of the PCell where the last RRCReconfiguration message including reconfigurationWithSync was received;

2> set the timeConnFailure to the elapsed time since the execution of the last RRCReconfiguration message including the reconfigurationWithSync;

1> else if the failure is detected due to Mobility from NR failure as described in 5.4.3.5, set the fields in VarRLF-report as follows:

2> set the connectionFailureType to hof;

2> if last MobilityFromNRCommand concerned a failed inter-RAT handover from NR to E-UTRA and if the UE supports Radio Link Failure Report for Inter-RAT MRO EUTRA (NR to EUTRA):

3> set the eutraFailedPCellId in failedPCellId to the global cell identity and tracking area code, if available, and otherwise to the physical cell identity and carrier frequency of the target PCell of the failed handover;

2> include nrPreviousCell in previousPCellId and set it to the global cell identity and tracking area code of the PCell where the last MobilityFromNRCommand message was received;

2> set the timeConnFailure to the elapsed time since the initialization of the handover associated to the last MobilityFromNRCommand message;

1> else if the failure is detected due to radio link failure as described in 5.3.10.3, set the fields in VarRLF-report as follows:

2> set the connectionFailureType to rlf;

2> set the rlf-Cause to the trigger for detecting radio link failure in accordance with clause 5.3.10.4;

2> set the nrFailedPCellId in failedPCellId to the global cell identity and the tracking area code, if available, and otherwise to the physical cell identity and carrier frequency of the PCell where radio link failure is detected;

2> if an RRCReconfiguration message including the reconfigurationWithSync was received before the connection failure:

3> if the last executed RRCReconfiguration message including the reconfigurationWithSync concerned an intra NR handover and it was received while connected to the previous PCell to which the UE was connected before connecting to the PCell where radio link failure is detected; and

3> if the PCell in which the radio link failure was detected was a result of cell selection and the T311 was not running at the time of PCell selection:

4> include the nrPreviousCell in previousPCellId and set it to the global cell identity and the tracking area code of the PCell where the last executed RRCReconfiguration message including reconfigurationWithSync was received;

4> if the last executed RRCReconfiguration message including reconfigurationWithSync was concerning a DAPS handover:

5> set lastHO-Type to daps;

4> else if the last executed RRCReconfiguration message including reconfigurationWithSync was concerning a conditional handover:

5> set lastHO-Type to cho;

4> set the timeConnFailure to the elapsed time since the execution of the last RRCReconfiguration message including the reconfigurationWithSync;

3> else if the last RRCReconfiguration message including the reconfigurationWithSync concerned a handover to NR from E-UTRA and if the UE supports Radio Link Failure Report for Inter-RAT MRO EUTRA:

4> include the eutraPreviousCell in previousPCellId and set it to the global cell identity and the tracking area code of the E-UTRA PCell where the last RRCReconfiguration message including reconfigurationWithSync was received embedded in E-UTRA RRC message MobilityFromEUTRACommand message as specified in TS 36.331 [10] clause 5.4.3.3;

4> set the timeConnFailure to the elapsed time since reception of the last RRCReconfiguration message including the reconfigurationWithSync embedded in E-UTRA RRC message MobilityFromEUTRACommand message as specified in TS 36.331 [10] clause 5.4.3.3;

2> if configuration of the conditional handover is available in the MCG VarConditionalReconfig at the moment of declaring the radio link failure:

3> set timeSinceCHO-Reconfig to the time elapsed between the detection of the radio link failure, and the reception, in the source PCell, of the last conditionalReconfiguration including the condRRCReconfig message;

3> set choCandidateCellList to include the global cell identity if available, and otherwise to the physical cell identity and carrier frequency of each of all the candidate target cells for conditional handover included in condRRCReconfig within the MCG VarConditionalReconfig at the time of radio link failure, excluding the candidate target cells included in measResulNeighCells;

1> if connectionFailureType is rlf and the rlf-Cause is set to randomAccessProblem or beamFailureRecoveryFailure; or

1> if connectionFailureType is hof and if the failed handover is an intra-RAT handover:

2> set the ra-InformationCommon to include the random-access related information as described in clause 5.7.10.5;

1> if available, set the locationInfo as in 5.3.3.7.

The UE may discard the radio link failure information or handover failure information, i.e. release the UE variable VarRLF-Report, 48 hours after the radio link failure/handover failure is detected.

NOTE 2: In this clause, the term ‘handover failure’ has been used to refer to ‘reconfiguration with sync failure’.